默认情况下,MySQL对所有GROUP BY col1,col2...的字段进行排序。如果查询包括GROUP BY,想要避免排序结果的消耗,则可以指定ORDER BY NULL禁止排序。 SELECT goods_id,count(*) FROM t GROUP BY goods_id ORDER BY NULL; 禁止不必要的ORDER BY排序 SELECT count(1) FROM user u LEFT JOIN user_info i ON u.id = i.user_id WHERE 1 = 1 ORDER BY u.create_time DESC; INSERT INTO t (id, name) VALUES(1,'Bea'), (2,'Belle'),(3,'Bernice');